Re: [PATCH v3 2/3] pmbus: add regulator support

[Guenter Roeck <linux@roeck-us.net>]

On Wed, Sep 24, 2014 at 12:57:55PM -0500, atull@opensource.altera.com wrote:
> From: Alan Tull <atull@opensource.altera.com>
> 
> Add support for simple on/off control of each channel.
> 
> To add regulator support, the pmbus part driver needs to add
> regulator_desc information, of_regulator_match information,
> and number of regulators to its pmbus_driver_info struct.
> 
> regulator_desc can be declared using default macro for a
> regulator (PMBUS_REGULATOR) that is in pmbus.h
> 
> The regulator_init_data can be intialized from either
> platform data or the device tree.
> 
> Signed-off-by: Alan Tull <atull@opensource.altera.com>
> 

Hi Alan,

Overall looks pretty good. Couple of comments inline.

> v2: Remove '#include <linux/regulator/machine.h>'
>     Only one regulator per pmbus device
>     Get regulator_init_data from pdata or device tree
> 
> v3: Support multiple regulators for each chip
>     Move most code to pmbus_core.c
>     fixed values for on/off
> ---
>  drivers/hwmon/pmbus/pmbus.h      |   27 ++++++++
>  drivers/hwmon/pmbus/pmbus_core.c |  133 ++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c/pmbus.h        |    4 ++
>  3 files changed, 164 insertions(+)
> 
> diff --git a/drivers/hwmon/pmbus/pmbus.h b/drivers/hwmon/pmbus/pmbus.h
> index fa9beb3..74aa382 100644
> --- a/drivers/hwmon/pmbus/pmbus.h
> +++ b/drivers/hwmon/pmbus/pmbus.h
> @@ -19,6 +19,9 @@
>   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
>   */
>  
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/of_regulator.h>
> +
>  #ifndef PMBUS_H
>  #define PMBUS_H
>  
> @@ -186,6 +189,12 @@
>  #define PMBUS_VIRT_STATUS_VMON		(PMBUS_VIRT_BASE + 35)
>  
>  /*
> + * OPERATION
> + */
> +#define PB_OPERATION_CONTROL_ON		(1<<7)
> +#define PB_OPERATION_CONTROL_SEQ_OFF	(1<<6)

Can those defines be more consistent ? Does it really need SEQ_OFF or can it
just be OFF ?

> +
> +/*
>   * CAPABILITY
>   */
>  #define PB_CAPABILITY_SMBALERT		(1<<4)
> @@ -365,8 +374,26 @@ struct pmbus_driver_info {
>  	 */
>  	int (*identify)(struct i2c_client *client,
>  			struct pmbus_driver_info *info);
> +
> +	/* Regulator functionality, if supported by this chip driver. */
> +	int num_regulators;
> +	const struct regulator_desc *reg_desc;
> +	struct of_regulator_match *reg_matches;
>  };
>  
> +/* Regulator ops */
> +
> +extern struct regulator_ops pmbus_regulator_regulator_ops;
> +
How about just pmbus_regulator_ops ? I don't see a double regulator_
variable name anywhere else in the code, and I don't really see the
benefit of it.

> +/* Macro for filling in array of struct regulator_desc */
> +#define PMBUS_REGULATOR(_name, _id)				\
> +	[_id] = {						\
> +		.name = (_name # _id),				\
> +		.id = (_id),					\
> +		.ops = &pmbus_regulator_regulator_ops,		\
> +		.owner = THIS_MODULE,				\
> +	}
> +

Any idea how/if we can get rid of the resulting checkpatch error ?

>  /* Function declarations */
>  
>  void pmbus_clear_cache(struct i2c_client *client);
> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
> index d6c3701..9ab8bd4 100644
> --- a/drivers/hwmon/pmbus/pmbus_core.c
> +++ b/drivers/hwmon/pmbus/pmbus_core.c
> @@ -29,6 +29,9 @@
>  #include <linux/hwmon-sysfs.h>
>  #include <linux/jiffies.h>
>  #include <linux/i2c/pmbus.h>
> +#include <linux/regulator/of_regulator.h>
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/machine.h>
>  #include "pmbus.h"
>  
>  /*
> @@ -1758,6 +1761,125 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
>  	return 0;
>  }
>  
> +#if IS_ENABLED(CONFIG_REGULATOR)
> +static int pmbus_regulator_is_enabled(struct regulator_dev *rdev)
> +{
> +	struct device *dev = rdev_get_dev(rdev);
> +	struct i2c_client *client = to_i2c_client(dev->parent);
> +	u8 page = rdev_get_id(rdev);
> +	int ret;
> +
> +	ret = pmbus_read_byte_data(client, page, PMBUS_OPERATION);
> +	if (ret < 0)
> +		return ret;
> +
> +	return !!(ret & PB_OPERATION_CONTROL_ON);
> +}
> +
> +static int _pmbus_regulator_enable(struct regulator_dev *rdev, bool enable)
> +{

Can you find a better name for this function ? After all,
it doesn't just enable the regulator, it also disables it.

> +	struct device *dev = rdev_get_dev(rdev);
> +	struct i2c_client *client = to_i2c_client(dev->parent);
> +	u8 val, page = rdev_get_id(rdev);
> +
> +	if (enable)
> +		val = PB_OPERATION_CONTROL_ON;
> +	else
> +		val = 0;
> +
> +	return pmbus_update_byte_data(client, page, PMBUS_OPERATION,
> +				      PB_OPERATION_CONTROL_ON, val);

					enable ? PB_OPERATION_CONTROL_ON : 0

would be much simpler here.

> +}
> +
> +static int pmbus_regulator_enable(struct regulator_dev *rdev)
> +{
> +	return _pmbus_regulator_enable(rdev, 1);
> +}
> +
> +static int pmbus_regulator_disable(struct regulator_dev *rdev)
> +{
> +	return _pmbus_regulator_enable(rdev, 0);
> +}
> +
> +struct regulator_ops pmbus_regulator_regulator_ops = {
> +	.enable = pmbus_regulator_enable,
> +	.disable = pmbus_regulator_disable,
> +	.is_enabled = pmbus_regulator_is_enabled,

No get_voltage support ?

[ Guess it isn't mandatory. We can add it later to get this going. ]

> +};
> +EXPORT_SYMBOL_GPL(pmbus_regulator_regulator_ops);
> +
> +#if IS_ENABLED(CONFIG_OF)
> +static int pmbus_regulator_parse_dt(struct device *dev,
> +				    const struct pmbus_driver_info *info)
> +{
> +	struct device_node *np_regulators;
> +	int ret;
> +
> +	if (!info->num_regulators)
> +		return 0;
> +
> +	if (!info->reg_matches || !info->reg_desc)
> +		return -EINVAL;
> +
> +	np_regulators = of_get_child_by_name(dev->of_node, "regulators");
> +	if (!np_regulators)
> +		return 0;
> +
> +	ret = of_regulator_match(dev, np_regulators, info->reg_matches,
> +				 info->num_regulators);
> +	of_node_put(np_regulators);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +#else
> +static int pmbus_regulator_parse_dt(struct device *dev,
> +				    const struct pmbus_driver_info *info)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static int pmbus_regulator_register(struct pmbus_data *data)
> +{
> +	struct device *dev = data->dev;
> +	const struct pmbus_driver_info *info = data->info;
> +	const struct pmbus_platform_data *pdata = dev_get_platdata(dev);
> +	struct regulator_dev *rdev;
> +	int i;
> +
> +	for (i = 0; i < info->num_regulators; i++) {
> +		struct regulator_config config = { };
> +
> +		config.dev = dev;
> +		config.driver_data = data;
> +
> +		if (pdata && pdata->reg_init_data) {
> +			config.init_data = &pdata->reg_init_data[i];
> +		} else {
> +			config.init_data = info->reg_matches[i].init_data;
> +			config.of_node = info->reg_matches[i].of_node;
> +		}
> +
> +		rdev = devm_regulator_register(dev, &info->reg_desc[i],
> +					       &config);
> +		if (IS_ERR(rdev)) {
> +			dev_err(dev, "Failed to register %s regulator\n",
> +				info->reg_desc[i].name);
> +			return PTR_ERR(rdev);
> +		}
> +	}
> +
> +	return 0;
> +}
> +#else
> +static int pmbus_regulator_register(struct pmbus_data *data)
> +{
> +	return 0;
> +}
> +#endif
> +
>  int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
>  		   struct pmbus_driver_info *info)
>  {
> @@ -1769,6 +1891,10 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
>  	if (!info)
>  		return -ENODEV;
>  
> +	ret = pmbus_regulator_parse_dt(dev, info);
> +	if (ret)
> +		return ret;
> +

You have the conditions wrong above.

If CONFIG_REGULATOR is not enabled, this will fail to build,
since pmbus_regulator_parse_dt is not declared at all in this case.

I can understand that you want to parse the dt early, but it would be
simpler to just parse it from pmbus_regulator_register(). It is only
relevant if regulators are configured anyway, and we don't really need
to optimize the code for the error case.

>  	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE
>  				     | I2C_FUNC_SMBUS_BYTE_DATA
>  				     | I2C_FUNC_SMBUS_WORD_DATA))
> @@ -1812,8 +1938,15 @@ int pmbus_do_probe(struct i2c_client *client, const struct i2c_device_id *id,
>  		dev_err(dev, "Failed to register hwmon device\n");
>  		goto out_kfree;
>  	}
> +
> +	ret = pmbus_regulator_register(data);
> +	if (ret)
> +		goto out_unregister;
> +
>  	return 0;
>  
> +out_unregister:
> +	hwmon_device_unregister(data->hwmon_dev);
>  out_kfree:
>  	kfree(data->group.attrs);
>  	return ret;
> diff --git a/include/linux/i2c/pmbus.h b/include/linux/i2c/pmbus.h
> index 69280db..ee3c2ab 100644
> --- a/include/linux/i2c/pmbus.h
> +++ b/include/linux/i2c/pmbus.h
> @@ -40,6 +40,10 @@
>  
>  struct pmbus_platform_data {
>  	u32 flags;		/* Device specific flags */
> +
> +	/* regulator support */
> +	int num_regulators;
> +	struct regulator_init_data *reg_init_data;
>  };
>  
>  #endif /* _PMBUS_H_ */
> -- 
> 1.7.9.5
>